World: r3wp

OK I'll try it

0 = length? port/locals

can be

empty? port/locals

and in your read actor, you'll then simply do:

either open? port [{read was invoked as `open rif:// + read`}] [{read 
was invoked directly as read rif://}]

>> read/seek rif://data/file 1
** Script error: cannot access locals in path port/locals/2
** Where: Get-RIF read
** Near: Get-RIF port number

OK andreas

Maybe also a simple `if not open? port [open port]` will suffice 
in your case.

(Within the read actor.)

But typically you'll also want to add code to close the port again, 
afterwards.

can't you paste the whole code somewhere ?

This automatic open close is not clear to me after Andreas there 
is no such automation? where is the magic? :-O

There is no magic.

Rebol [
    file: %prot-rif.r
    title: "RIF protocol"
    author: "Pavel"
    rights: 'PD
    date: 13-Aug-2010
    ]

;; Local functions

Append-RIF: func [port [port!] record [binary!] ][


 write/append port/locals/2 to-binary length? head port/locals/1		;index 
 port the end of data file will be beginning of new record

 write/append port/locals/1 record							        ;data port new record 
 into data file


 return shift length? head port/locals/2 -3					        ;number of 
 records 8 bytes per record
]


Get-RIF: func [ port [port!] i [integer!] /local numentry indexpos 
recpos recend value ][


    numentry: shift length? head port/locals/2 -3                    
       ;number of records 8 bytes per record


 if any [i = 0 i > numentry] [return none]                        
    ;numbering starts at 1 ends at file end


 indexpos: multiply subtract i 1 8					                ;compute index 
 offset
	recpos: to-integer read/seek/part port/locals/2 indexpos 8

  either ( (8 * i) = length? head port/locals/2 ) [				;last record 
  special case
		recend: length? head port/locals/1
		][

  recend: to-integer read/seek/part port/locals/2 add indexpos 8 8		;internal 
  record
		]

 return read/seek/part port/locals/1 recpos subtract recend recpos
]

;; Scheme definition
make-scheme [
	name: 'rif
	title: "RIF Protocol"
	spec: make system/standard/port-spec-head []
    awake: none

	actor: [
		open: func [port [port!] /local path ] [
            parse port/spec/ref [thru #":" 0 2 #"/" path:]
            append port/spec compose [path: (to-file path)]
            port/locals: copy []
            either (0 = length? port/locals) [

                append port/locals open/seek rejoin [port/spec/path ".dat"]

                append port/locals open/seek rejoin [port/spec/path ".idx"]
                ][

                port/locals/1 open/seek rejoin [port/spec/path ".dat"]

                port/locals/2 open/seek rejoin [port/spec/path ".idx"]
            ]
        return port
        ]

        close: func [port [port!]] [
            foreach  port port/locals [close port]
        ]

        read: func [port [port!] /seek number [integer!] ] [
            Get-RIF port number
        ]

        write: func [port [port!] record [binary!]] [
            Append-RIF port record
        ]

    ]
]

arghh... not here ;-)

There are action!s in R3, which operate in port!s.

If you define custom schemes, you can implement how those actions 
behave for ports using your scheme by writing what we call "actors".

This is the elementary principle to understand.

It is elementary dear Watson :-)

Watson <- me here

http://www.rebol.net/wiki/Schemes:Notes#Actors

try to open the port at first
and then call your read function with it

when you directly use read on a path, i'm not sure that your 'open 
function is called

Ah, all documented in the wiki :)

OK lets try it better, thanks guys for lesson learned!

(Refresh, if you have the page open. I just fixed the formatting.)

But I think I'll refine the example and add an open? actor as well.

I made it 
read: func [port [port!] /seek number [integer!] ] [

		either empty? port/locals [
		open port
            	return Get-RIF port number
		][
		return Get-RIF port number
		]

and it works now

Btw Pavel, in my virtual-block scheme, the reason why I rebound the 
actors, is that I don't like to use nasty long path to acces my locals.

I hope close is in garbage collector as mentioned in wiki

And second is more speed?

It should be :-)

can't you 

return get-rif either empty? ...

or 

if empty? port/locals [ open port ]
get-rif port number

graham it is better thanks

we should rename this group to !REBOL schemes

but we"re missing a rename actor

we can use a proxy actor

Ahh.... I can rename :)

Pavel, the names for the get/put operations of key-value stores are 
PICK and POKE.

We have a separate !REBOL3 Schemes group on purpose. Please don't 
rename it.

We didn't have a separate !REBOL3 Schemes group.

We created a bunch of spinoff groups because !REBOL3 was getting 
too busy.

I guess you took the "!REBOL Schemes" too literally. It is "!REBOL3 
Schemes" Graham intented, and in fact, already renamed this group 
to. (It was "!REBOL3 Network Schemes" previously.)

intended*

OK, cool. That is shorter :)

Yeah. And more approriate :)

Wasn't this group orginally named "Graham's foray into scheme arcana" 
 or something similar??

scheme on you

Pavel, you were right the first time in trying to implement GET/PUT 
actors, but you got the names wrong. Try again with PICK and POKE.

get: :pick
put: :poke

Metaphorically, yes. Literally, that will break REBOL :)